Angular accelerometer



Jan. 22, 1957 Filed May 24. 1954 L. D. STATHAM ANGULAR ACCELEROMETER 4 Sheets-Sheet l INVENTOR. Lou/s D. 5TH THHM ATTORNEY.

Jan. 22, 1957 i D. STATHAM 2,778,624

ANGULAR ACCELEROMETER Filed May 24, 1954 4 Sheets-Sheet s IN VEN TOR. Louis D. STFITHHM Ln B Jan. 22, 1957 D. STATHAM 2,778,624

ANGULAR ACCELEROMETER Filed May 24, 1954 4 Sheets-Sheet 4- ATTORNEY 2,718,621. .ANGULAR ACCELEROMETER Louis D. Statham, Beverly Hills, Cal if., assig'r1or to-Statham Laboratories, Inc., Los Angeles, Calif., a corpora tionofCalifornia Application May 24, 1954,5snnis 431,764;

171Clain1s. (c1. 26;4 -.1)

This application is a continuationdn part of applications Serial'No'. 241,539, filedAugust 13, 1951, and Serial No. 328,416, filed DtiCBmbr 29, 195 2.o

This invention relates to a motion responsive' devic'e for: indicating and recording the magnitude and nature of motions of an object in space. It belongs tothe general class of motion sensing devices such as'accelerometers. The conventional examples of such systems Iinclude devices in which the eflfective inertial mass is a'fsolid mass suspended on springs and the nature and magnitude of the displacement of the'mass on the springs are a measure of the magnitude and nature of the r'notioiiz.

Instead of using a solid mass suspended on springs, as in theprior art, I employ a liquid mass as the effective inertial mass and measure displacement of the liquid mass relative to the container subjected to the motionto be sensed.- l J Since I use a liquid mass instead of a solid inertial mass, I may use'a large mass Without introducing a large hinge, such as would be necessary were I .to'use a s olid mass of equivalent weight. Such a large weightwould require a large hinge or'pi'vo'ts-or springs in order to with; stand mechanical shocks. Because as stated abov'e Iuse, as the effective inertialmass, av liquid mass and'fdo not employ a solid mass as the fiective inertial rnass, I avoid the use of hinges and pivots of the size necessary where the effective inertial mass'is solid rather than liquid,

2,778,624 Patented Jan. 22, 1957 device is responsive. The limit of this increase is set by'the permissible displacement of the paddle as imposed" by the nature of the device used to check the motion of the paddle.

In the instant invention the liquid mass serves as the rotor so that the weight of the paddle which must be supported along the sensitive axis can be made extremely low. Bafiies are fixedly mounted above and below the paddle, such baflles being disposed parallel to the axis of the paddle and spaced closely adjacent thereto.

Thus, the separation between the'edges of the paddle and the inner chamber walls form fluid communication paswalls of the container, and between the'paddleandthe' baffies. The paddle will deflect angularly until the elastic' sageways, and the spaces between the bafliesand paddles form another series of fluid communicating passages. When the instrument is subjected to an angular accelera tion,'the inertial forces will cause the liquid to rotate and. develop a pressure against the paddle" as theliquid is forced between the edges of the paddle and the adjacent restraint of the flexure and the pickofi (mechanism for sensing the motion) balances the forces on the'paddleQ The novel structure of the invention can be readily adapted to the use of a varietyofpickofi mechanisms.

It is not necessary for the paddle to have any substantial mass; all that isrequired is that it be structurally rigid Preferably and ideally, the weight of the paddle in .airf may be made equal to the weight of the liquid displaced by the paddle when it is mounted inthe device where it is immersed'in the liquid forming the efiective inertial. mass. Such a paddle may be termed buoyant. Accord-' ingly, the paddle is preferably constructed as. a hollow member with sealed ends so that itsweight, when im-' mersed in theliquid, is relatively small,.and ideally may be made substantially equal to zero. The buoyancy're-J duces the weight of the paddle in liquid. The use of a buoyant paddle also eliminates the. necessityjfor careful balance of the suspended mass to minimize the sensitivity By placing a movable member immersed in the liquid 3 thrust on the movable member resultingfrom the relative displacement of the liquidand the container for the liquid.

The motion of the liquid is damped by viscous drag. In order to increase the damping effect, I have added an additional damping means, by'causing the fluid to flow through an orifice, so that a passage of liquid occurs on the passage of the liquid through the-orifice as a result of the relative motion of the liquid and the container walls. The result of this arrangement not only gives an additional damping effect but has the property that it tends to maintain a more nearly constant damping coefficient for the instrument,notwithstanding temperature changes and consequent changes in viscosity of the liquid, than would be obtained if the orifice is not employed.

Additionally by providing an' endless liquid conduit over the movable member and around the'container of the system, so that a circulation of the liquid is obtained, the device will sense progressive increases in the displacement of the liquid mass and the'container onincreaseof the magnitude of the function of'the motion to which the of the instrument to linear accelerations. It also reduces the effect of angular velocity on they displacement of the paddle andifthe paddle hasan insubstantial submerged mass, the paddle may be made linsensitive toangular velocity. 4

These and other features and objects of my invention will be further described in connection with the accompanying drawings, wherein:

Fig. l is. aplan view of a preferred embodiment of my invention, with parts broken away and parts in section forclarity;

Fig. 2 is a vertlcal broken section taken on 2 -2 of Fig. 1;

Fig. 3 is a vertical section onjline 33 oij-Fig. 2; Fig. 4 is an irregular section on line 44 ofFig. 2;

Fig. 5 is a view taken on line 5-5 of Fig. "3, looking in the direction of the arrows; i T; Fig. 6 is a perspective View of.-anelement. of the in-; vention device; 1 v

Fig. 7 is a perspective View of another element of the device; e Fig. 8 is an isometric view of the paddle assembly of the device; and 1 Fig. 9 is a section taken on line 9-9 of Fig. 1. Referring particularly to Figs. 1 and 2, the container 1 is shown as a cylinder, but may be of any shape provided that it is a closed container. The container is closed by a bottom 2 and a tops, The'bottom 2 carries a depending circular flange 4, to the lower end of which is secured a removable cover 5, held in place by snap mam case 1, with the lower end portion of member 3 resting on a horizontal shoulder 4. formed by a recess in the wall Secured to top 3 b means of ,bolts 10; passing ht u h an p a enw r e en in an e 1.1 rth ten-.3. is T1PY?Ih .l d p d n an e 1 .Po itioned between the lower end of flange 13.;and the tp of. flange 11 is a flexible-diaphragm 14 held in placeby th b lt 1. iii-leas :11 h s! 8 9 1 therein to acconimodate an O ring 9 forseal ing purposes. v

A seeainfiss- Lan 4, ua s b k t member a n r i ah t h k' ra n '11 a 2. a tached to theba .'2 ,by means of screws 15. located at the'c nersof.inerriber17;v v.

vAn rin'g seal Fig.2 and described below. Secured to e'a'ch of plates 2Q; and ZO' by bolts Z1 and nuts"2 2. is a bafile 23, 'th e lower ends of which extehd somewhat below the lower ends of platesjo and 2 0'. Bolts 21 pass through slots in baihes 23, the slots being provided .for vertical adjustment ofthe'baiiilesfto vary the distance between the lower edges of the b aflies and the, paddle .35 described b'e1ow. LBaitieS 23 extend in alignment with each other a n aQi' mfiw ih lt in' 1 n thirmltet e d are located'adjacentjtherespective opposite ends of plates 29. .2 2 Q i t e ge th bafii'es ing spacied ashort distance fromithe adjacent in r walls 'lhe. inner "edges 23" 'of l5afii'es. 23 are located directly above the opposite side edges of bracket smbsr. Aira 9 Q s bl f 5 b p 'w w svame lengthas baffles 23 are'positioned directly new and in a i nme t. w th. he upper 2. 't f p i i md al ea .9? affle .5. h a b b f i id a l to 'the adjacent lower longitudinal edges of bafile's 23. 'I fheouter edges ofbafhes 25 are also spaced a jshortdi'stance from the container wall sections and Q15", "although if desire d, the outer edges ofi either or both fles ZS andiZS or of ejither orb'o'thplates and 20"iiiay touch-theadjacentwall sections. ;1"he inner bfids 12 5" of baffles abut a'gain'st opposite "sides of bracket i'iimber 17 (see Fig. 9). Baifie'sib' are secured lbynieans ofbolts '27 and nuts 2810 plates '29 and) located at opposite sides of container 1 and in verticalalignm'ent withplat'es 20 and ZO, respectively. Bolts 27 pass through slots 25" in baffies 25 for vertical adjustniijtf'of "theba'ffiesr Plats29 and '29 'areattaclied toa pair of opposite support members 30 and 3h, respectively/which support'rnernbe rs are in ttiin "respectively secured by meansbr bolts 31 to opposite sides of bracliet poftions 3 2 an'd 17. v i I p Posit'io'ned inthe' space between and parallel to the adjacent longitudinal edges of baffies zs'aha 25 (see Figs. 2, 4,'8fand 9),J'is a buoyant paddle 35 of low Weight t he afdrthen tioiled liquid, the paddle iextendifig diainetrically er; the e naarieai container. generally in the form of lan' elongat d liollow 'nierhber with the: ends saled; The pa'clille or instant'ernbo'clih'ient is shown-as being" formed .of two aligned hollow cylinders 36 with their outer ends sealed by threaded The '"paddle "is caps 37. The inner adjacent e'iitls'o'f reduced diameter of cylinders 36 are each threaded as at 37' into opposite ends of a central hollow oblong paddle mount 38. However, a paddle of any structural shape or configuration 5 may be employed according tov the invention, so long as the weight of the paddle in the liguid is maintained small according to the invention Theoretically, it isnot necessary for the paddle t'o have any apparent weight when submerged in the liquid; i. e., .it n1 ay be compl t b. 9 ant; a1l, that is re qiiir e' that it sttiiti'I ally 'd'; The paddle may be constructcd'of aiiy triaterial rring the foregoing mass {characteristics on the paddle, such as'rna'gnesiu'm, aluminum, plastic and the like. The reason for this i s th at the liqtri dn iass as Will be more clearly seen hereinafter, serves as therotor.

The outer edges of'the paddle 35 may touch the adjacent Wall sections 15 and 15 so long as the paddle is free to rotate ove 1 the wall. However; this will reduce the resolution of the exit, and it will not to as low values of acceler ion 1c end gaps are provided. I the "preferredfe'm odir'nent of my invention both 'e'n of the'paddleare spaced from thewall .sections lS l d 115 to g'ivfe orifices 38 of 'siie to P QQPQ th es d p ng. fi 'ct. 4 t

Al th ough soinefdamp ng is 'obt'aii'ed'by reason of the orifices 38 bletween'the ends of th'e'paddle andthe 'adjacent, wall sections of the container as described above, an additional damping e'iiect is obtained along with a high natural frequency according to the instant improve ents hy reasonof thepar'allel slots ifljor'med between the paddle and the 'ad 'aeeriredges of battles Band 25. The snacifig 'v j h n v. f tionary baffles -is in'ipor because as these gaps are increased area, the damping ratio at any given temperature for any given oil in the instrument will increase -V l 1 l When thefifist'rjurnerl t is subjected'to an angular aclr'att n,. tire;liqnid i the -"gaps o 's'lots f40 acquires velocitisjgf atly in excess ofjthevelocity of 'the' main mass of the liquid rotor. v ce the kinetic energy of the li'ciiiidfiril'fhefgafis is proport onal to the""s qnare "of the velocityjde'spitefth'e low rna'ssfof thehqiiid "in the gaps, a r'ediifc tion'in the natural frequency of the instrument will 5 fs fli f ns f iniim hd Extirijmetal fsjrvationsshow'that" optimum size oftheg'aps f40"rn ay befattaind yvlie'fe'n purious'rnodes of vibration'aredispreciable reduction in natural frewhich in common with the nstrup y thecoinpanibnfcassfhave the followrties The r'an'geofthedeyice, i.""e., "th h ax'i device is sensitive is il heig 'ht, e. f'g., the ately one-hair /2 F I V bfafiles. Thenatu'ral frequency s nyerselyfproportional to. the active oil height. T ra frequency varies directly as "the 'r'aii'g'e, fas

thfthefs'yste'm in 'wlii eh ar resiliently sus- Solidis theetfective'inertial mass, in 'which case the uralffrequency varies directlyas thesqua r'e root Thus keeping all other pafarneters 6onof "the instrument increases "a the 'afctiye or i "mute" p a V H ater "is the length 'ofi-th'e "paddle. ilh nature frequencyjfdecrea ses as the paddle diameter p The paddle mounted on a leaf spring 'typeiCardan suspension j'so as tdpivot on'the central anis of hecentainer 1. A The pivotedmounting shown in 'Fig. l'c'b'n'sists of. aa i lat y p ac d l s 45 lmbu t dgv. t by means of boltsl-lo an d -16 Secured to the angi la by means of clamps 46 (see Fig. 6 and bolts 417- passing throughthem isva V-shapedspring48 (see Fig.1.) having a planar base 49, the angles formed by the legs 50 of the Vandthe-base being equal. I The base ,of, the spring is connected by a' screw 5,1,to the centra1" h ub, 52 of. the paddle 35 so as to put the axis of the paddle on a; line passing. through the diameter of the'cylindrical container. The paddle 35 can thus pivot about the-central axis of the container on the spring 48. 'lhe angular motion of the paddle is limited byf me'ans of two limit motion stop screws 53 which may be. adjusted on the lugs 45. a

The hub 52 of the paddlefhasa symmetrical boss 52' on opposite sides of the hub, and a screw 51"olffthe same weight and contour as screw'51isfastened to the opposite side of the hub. This hub structure makes the paddle completely symmetrical, that is, the paddleisfcompletely balanced in weight and is symmetrical in form fabout a longitudinal axis through the central axisof thefcylindrical paddle. and also'about an axis perpendicular thereto and passing'through the paddle pivot point 35' which is substantially at the" intersection of the legs 50 of spring 48. While the 'paddle'i s substantially completely balanced in the embodiment shown, if desired, art additional spring such as 48 may be connected to the hub 52 of the paddle directly opposite and in the same manner as spring 48, and suspended in a similar manner 'with the legs of the additional spring secured to lugs "84 onibracket 17.

Connected to opposite ends respectively ofbrackets 17 and 32 by means of screws 55'are a pair 'of blocks 56 and 57. Blocks 56 and "57 have longitudinally extending brackets 56' and 57' integrally connected to the lowerportions thereof, these brackets resting on and being secured to the square bracket 17' by means of screws 58. Block 56 carries two sets of pins, one set being positioned adjacent the other. One set of such pins consists of three pins 60, 63., and 62, pin 61 being positioned between but farther from paddle"35=than pins 60 and 62. The

other set of pins also consists-"0f three pins 63; 64 and 65 located with respect to each othersimilarly to pins 60, 61 and 62, intermediate-pin 64 being'positioned' directly opposite intermediate pin 61, i. e., on-a line parallel to the axis of paddle 35. Block 57 also'ca'rries two adjacent sets of pins, one set being composed ofthreje pins, 60, 61 and 62', situated similarly to and directly-oppm site (i. e. on a line normal to the axis of paddle 35) pins 60, 61 and 62 on block 56', and-the other set consisting of pins 63', 64' and 65' located-similarly toand directly opposite pins 63, 64 and 65 on block 56. Positioned: on a lug 38 formed on paddle mount'38" (see Fig. 9) in a plane normal to the-axis of thepaddle and passing through pins61 and 61 -is a pin 70, and also located on lug 38"a on the paddlemount in a plane normal to the axis of the paddle and passing through pins'64and64 is apin71. i y

A strain sensitive wire 72 is wound in tension between pins 61 and 70 in a loop, one end of the loop terminating at pin 60 and the other end terminatingat pin 62. A strain wire 72'v is also wound in tension between pins 61 and 70 in a loop, one end of the loop. terminating at pin 60 and the other end terminating-at pin'62'. Inthe same manner a strain wire 73 is wound in tension in aloop between pins 64 and 71, the opposite ends of the wire terminating at pins 63 and 65; and a strain wire 73' is wound in tension in'a loopbetween pins 64'. and 71, the opposite ends of the Wire terminating at pins 63 and 65'. All the pins are electrically insulated and the wires are out of contact with the frame and with each other. qThe ends of each of the four wires 72, 73, 72' and 73' are respectively connected by conductors suchas .90, to four pairs of terminals 75,76, 77 and 78 located .in blocks 56 and 57, which terminals in turn are connected by conductors (not shown) to terminals 79 (see Fig. 3) extending through bottom 2 of the device. The latter terminals are connected in a conventional Wheatstone bridge arrangement to the four outer terminals 80 located on the periphery of flange 4. j

It will be seen that angular motion at the paddle '35,

e. g., in a clockwise direction as viewed in -Fig.-, 1, will cause pin 70 to move toward block 56 and away from block 57, and will cause pin-71 to move toward block 57' and away from block 56. This-action relaxes the tension in' wires .72 and 73', and increases the tension in wires 72' and 73,'since the pins on blocks 56 and 57 are stationary. Ifthe mass of liquid in the container causes the paddle to move counterclockwise, wires 72 and 73 are increasingly tensioned and the tension in wires 72' and 73 is relaxed. Suitable motion limiting stop screws 83 pass through lugs 84 secured'to the bracket 17 by screws 16 and 16. p

The case or containerl may be completely filled with liquid through a fill hole stoppered by a screw 85 (see Fig. 5) and the fluid enters and fills the chamber 86 between thebottom andtop members 2 and 3 of the device, and passes into and fills the chamber 87 underneath the diaphragm 14 through ports 88. Suitable air breather holes 89 are provided in the flange 13.

The liquid employed maybe any liquid but, I desire to choose a fluid having a low viscosity temperature susceptibility even though it be of low density, particularly if it have also a low value of itscubical coefficient of I expansion, rather than to choose a liquid of high viscosi'ty temperature susceptibility and high density, particularly if it also have a high value for its cubical coeificient of expansion. This leads me to select as my preferred liquid an oil and preferably the synthetic silicone polymers which have flat viscosity temperature lines on the ASTM chart. Thus, by a proper selection of the magnitude of the design parameters of my instrument as described above, I may select the desired damping ratio which willi remain sensible constant over a wide range of viscosities of the damping oil.

A higher natural frequency for a given range can be I obtained in the device described herein by increasing the diameter of the liquid rotor. Further, a higher natural frequency can be obtained for a given diameter of case and for :a specific range by increasing the ratio of height of liquid mass to height of the paddle.

While I have disclosed an electrical resistance strain gage type transducer as the motion-sensing device, it will be understood by those skilled in the art that any other suitably designedtransducer, such as an inductive type transducer illustratedin my above noted application Serial No. 328,416, or other equivalent devices may be employed.

While I have described a particular embodiment of my invention for the purpose of illustration, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention as set forth in the appended claims.

Icl'aim:

l. A motion sensing device, comprising a case, a closed chamber in said case, a liquid inertial mass in said chamber, a paddle in said chamber immersed insaid liquid, said paddle being of substantially no eifective mass when immersed in said liquid, said liquid being the'inertial mass and the effective rotor of said device, a mounting for said paddle fixedly mounted in said chamber and connected to said case, said paddle being movably mounted in said chamber with one edge or" said paddle adjacent, but out of contact with, an enclosing wall of said chamber, the separation between the edge of the paddle and said wall forming a fluid communicating passageway, said paddle being positioned on said mounting for limited motion on said mounting with respect to said case on acamen eqmmuni atipg assageway in said chamber non drie side oi said paddle to theother side.

3 motion sensing device, cor nprkin'g a ease, a elosed chamber said case, a liquid inertial inass in said chamher, a paddle in said shaman-immersed insaid' liquid, said paddle being of substantially no ei fective mass when immersed in said liquid, said liquid being the inertial mass and theetfec'tive-roto'r of said device, a mounting for s ai cl paddl e fixedly rn ou nted in said chamber and eonnecte'd to said case, said paddle being mo /ably mounted in said chamber with one edge of said paddle adjaejajn, but out of bones: with, an enclosing wall or said engineer, a bafli epositioned in said member extending along s aid pad'dle and spaced ther'efiom, 'a liquid communication passageway for fluid movem'entfroin one side offsaid paddle to the other Side (if said paddle and be tween the edge of said paddle and said wall and between said paddlefandsaid bafile, said paddle being positioned on saidmouiiting for limited angular'inotion on said mounting with respect to said case on angular acceleration of said case, said mounting restraining motion or said paddl'e withr'espect to said case in the absence of angular acceleration of said case, and means for sensing said rn'dtion. i

4. A motion sensing device, comprising a case, a closed chamber in said case, said chamber being in the form ot' 'a cylinder and having opposing cylindrical walls, a liquid inertial mass in said chamber, a paddle of substantially no effective mass when immersed in said liquid, said liquid being the inertial mass and the effective rotor of said device,a spring hinge for said paddle, said spring hinge being connected to said paddle, a mounting in said chamber for said hinge,;said mountingbei'ng connected to said case and to said hinge, said paddle being rotatably mounted about said spring hinge on the axis of said cylinder for limited angular motion of said paddle about the said axis and with respect to said case on angular acceleration of said case, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, said paddle extending from one Wall to the opposing wall and immer'sed in said liquid, opposing edges of said paddle being adjacent the opposing cylindrical walls, and a motion sensing device connected to said paddle to sense the angular displacement of said paddle. A motion sensing device, comprising a case, a closed chamber in said case, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertialmass in said chamber, a paddle of substantially ho effective mass when immersed in said liquid, said liquid being the inertial mass and the effective rotor of said'device, a spring hinge for said paddle, said spring hinge being connected to said paddle, a mounting in said chamber for said hinge, said mounting being connected to said case and to said hinge, said paddle being rotatably mounted about said spring hinge'on the axis of said cylinder for limited angular motion of said paddle about the saidaxis and with respect to said case on angular acceleration of said case, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, said paddle'extendin'g from one wall to the opposing wall and immersedin said liquid, opposing edges of said paddle being-adjacent the opposing cylindrical walls, an edge inei ti'al "mas's in said chamber, a paddle of substantially no "effective mass when immersed in saidliquid -said li ql lid being the inertial mass and me 'eneetive rotdr of said device, a sp'ringthinge ior'said paddle, said spring 8 hinge Being connected to said paddle, a mounting-1a said chamberfor'Ts'aid'hinge,'said mounting being ed to said seand tosaid hinge, said paddle being rotatably ted about saidspring hinge on'the axis of said cyliirde for 1i fed a gular motion of said paddle about the jsaid-faxisand with respect to said case on angular accelerationof said case, said hinge restraining motion of said paddle with fespectto said case in the absence of aii gularacceleration of said case about said axis, said padaie-enandin' nam one wall to the opposing wall and immersed in said liquid, opposing edges of said paddle being adjacent the opposing cylindrical walls, an edge "of cash side ofthe paddle being spaced fronrthe adjacent wall bit the chamber, ab'a'file positioned in said chamber parallel tosaid paddle and spaced therefrom, and a motion sensing device connected to said paddle to sense the angular displacement of said paddle.

7-. A'motion'sensing device 'c o'mpi'isi'n g a case, 'clds'ed chamber'in said case, said chamber being in the form d'f a cylinder and having bppo sing cylindrical walls, a liquid inertialimassin said chamber, a paddle in said chamber and immersed in said liquid, said paddle being of substantially no effective mass when immersed in said liquid, said liquid being the inertialmass and the efiectivefroto'r of said device, a hinge for said paddle, said hinge being connected to said paddle, amounting for said hinge in said chamber, said mounting being connected to said case and to said h inge, said paddle being rotatabl y iimunted about said hinge on the axis of said cylinder, for limited angular motion of said paddle about saidaxis and with respect to said case on angular accclcrationof said case'about said axis, said paddle extending from tine wall to the opposing wall, opposing edges of said paddle being adjacentthe opposing cylindrical walls, said hinge restraining motion of said paddle with respect to said caseabout said axis, and a motion'sensing device connected'tosaid paddle to sense the angular displacement of said paddle with respect to said case.

8. A motion sensing device comprising a case, a closed chamber in saidcase, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertial mass in said'chamber, a paddle in said chamber and immersed in said liquid,- said paddle being of substantially 'no' efliective mass when immersed in said liquid, said liquid being the inertial mass and the efit'ective rotor of said device, a hinge for said paddle, said hinge being connected tosaid paddle, a mounting for said hinge in said chamber, said mounting being connected to said case and .to.said;hinge,.said paddle being rotatably mounted about said hinge on the axis of said cylinder, for limited angular motion of said paddle about said axis and with respect to said case on angular acceleration of said case abou't said axis, said paddle extending from one wall to the opposing wall, opposing edges of said paddle being adjacent the opposing cylindricalwalls, an edge of said paddle being-spaced from the adjacentcylindricall wall'of the case, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, and a motion sensing device connected to said paddle to sense the angular displacement of said paddle with respect to said case.

9. Amotion sensing device comprising a case, a biased chamber in said case, "said'chamber being inthe'forin of& cylinder and having opposing cylindrical walls, a liquid inertial mass in said chamber, a paddle in said chamber and immersed in said liquid, said paddle being of sub"- stantially'nO effective 'mass when immersed in said liquid, 'said liqui d being the inertial mass and the efle'ctiv'e rotor of said device, a hinge for said paddle, said hinge being 'eonnected tosaid-paddle, amounting for said hinge in said ehafnber, said mount ing being eonnected to-said"case and to said hinge, said paddle being rota'tably mounted abouts" hinge on the ax-is bf said cylinder, for limited angular anoti on of s'aid paddle -about said axis and respect to said case on angular acceleration of said case about said axis, said paddle extending from one wall to:

the opposing wall, opposing edges of said paddle being adjacent the opposing cylindrical walls, an edge of each side of the paddle being spaced from the adjacent wall of the case, a baflie positioned in said chamber parallel to said paddle and spaced therefrom, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, and a motion sensing device connected to said paddle to sense the angular displacement of said paddle with respect to said case.

10. A motion sensing device, comprising a case, a closed chamber in said case, a liquid inertial mass in said chamber, a hollow paddle in said chamber immersed in said liquid, said paddle being of substantially no ef-, fective mass when immersed in said liquid, said liquid being the inertial mass and the effective rotor of said de vice, a mounting for said paddle fixedly mounted in said chamber and connected to said case, said paddle being movably mounted in said chamber with one edge of said paddle adjacent, but out of contact with, an enclosing wall of said chamber, the separation between the edge of the paddle and said wall forming a fluid communicating passageway, said paddle being positioned on said mounting for limited motion on said mounting with respect to said case on acceleration of said case, said mounting restraining motion of said paddle with respect to said case in the absence of acceleration of said case, and means for sensing said motion.

11. A motion sensing device, comprising a case, a closed chamber in said case, a liquid inertial mass in said chamber, a hollow paddle in said chamber immersed in said liquid, said paddle being of substantially no effective mass when immersed in said liquid, said liquid being the inertial mass and the efiective rotor of said device, a mounting for said paddle fixedly mounted in said chamber and connected to said case, said paddle being movably mounted in said chamber with one edge of said paddle adjacent, but out of contact with, an enclosing wall of said chamber, a bafile positioned in said chamber extending along said paddle and spaced therefrom, a liquid communication passageway for fluid movement from one side of said paddle to the other side of said paddle and between the edge of said paddle and said wall and between said paddle and said b aille, said paddle being positioned on said mounting for limited angular motion on said mounting with respect to said case on angular acceleration of said case, said mounting restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case, and means for sensing said motion.

12. A motion sensing device, comprising a case, a closed chamber in said case, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertial mass in said chamber, a hollow paddle of substantially no effective mass when immersed in said liquid, said liquid being the inertial mass and the effective rotor of said device, a spring hinge for said paddle, said spring hinge being connected to said paddle, a mounting in said chamber for said hinge, said mounting being connected to said case and to said hinge, said paddle being rotatably mounted about said spring hinge on the axis of said cylinder for limited angular motion of said paddle about the said axis and with respect to said case on angular acceleration of said case, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, said paddle extending from one wall to the opposing wall and immersed in said liquid, opposing edges of said paddle being adjacent the opposing cylindrical walls, and a motion sensing device connected to said paddle to sense the angular displacement of said paddle.

13. A motion sensing device, comprising a case, a

I 10 closed chamber in said case, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertial mass in said chambena hollow paddle of substantially no efiective mass when immersed in said liquid, said liquid being the inertial mass and theetiective rotor of said device, a spring hinge for said paddle, said spring hinge being connected to saidpaddle, a mounting in said chamber for said hinge, said mounting being con-nected to said case and to said hinge, said paddle being rotatably mounted about said spring hinge on the axis of said cylinder for limited angular motion of said paddle about the said axis and with respect tosaid case on angular acceleration of said case, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, said paddle extending from one wall to the opposing wall and immersed in said liquid, opposing-edges of said paddle being adjacent the opposing cylindrical walls, an edge of said paddle being spaced from the adjacent cylindrical wall of the chamber, and a motion sensing device connected to said paddle to sense the angular displacement of said paddle.

14. A motion sensing device, comprising a case, a closed chamber in said ,case, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertial mass in said chamber, a hollow paddle of substantially no efiective mass when immersed in said liquid, said liquid being the inertial mass and the effective rotor of said device, a spring hinge for said paddle, said spring hinge being connected to said paddle, a mounting in said chamber for said hinge, said mounting being connected to said case and to said hinge, said paddle being rotatably mounted about said spring hinge on the axis of said cylinder for limited angular motion of said paddle about the said axis and with respect to said case on angular acceleration of said case, said hinge restraining motion of said paddle with respect to said case in the absence of angular acceleration of said case about said axis, said paddle extending from one wall to the opposing wall and immersed in said liquid, opposing edges of said paddle being adjacent the opposing cylindrical walls, an edge of each side of the paddle being spaced from the adjacent wall of the chamber, a bafile positioned in said chamber parallel to said paddle and spaced therefrom, and a motion sensing device connected to said paddle to sense the angular displacement.

of said paddle.

15. A motion sensing device comprising a case, a closed chamber in said case, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertial mass in said chamber, a hollow paddle in said chamber and immersed in said liquid, said paddle being of substantially no effective mass when immersed in said liquid, said liquid being the inertial mass and the effective rotor of said device, a hinge for said paddle, said hinge being connected to said paddle, a mounting for said hinge in said chamber, said mounting being connected to said case and to said hinge, said paddle being rotatably mounted about said hinge on the axis of said cylinder, for limited angular motion of said paddle about said axis and with respect to said case on angular acceleration of said case about said axis, said paddle extending from one wall to the opposing wall, opposing edges of said paddle being adjacent the opposing cylindrical walls, said hinge restraining motion of said paddle with respect to said case about said axis, and a motion sensing device connected to said paddle to sense the angular displacement of said, paddle with respect to said case.

16. A motion sensing device comprising a case, a closed chamber in said case, said chamber being in the form of a cylinder and having opposing cylindrical walls, a liquid inertial mass in said chamber, a hollow paddle in said chamber and immersed in said liquid, said paddle being of substantially no efiective mass when immersed in said liquid, said liquid being the inertial mass and the 11 e'fictive-rotor of saiddevic'e, ahin'ge forsaid paddle, said hinge being connected to said paddle, "a mounting for said hinge in said chamber, said mounting being eonne'ct'ed't'o saidcase and to said hinge, said paddle being rotatably' mounted about said hinge on the axis of 'said cylinder, for limited angular m'otiomof saidpaddle about said axis and with respect "to said case on a'ngnl'ar accelli k motion sensing device comprising a case, a

lose'dcha'mber in saidcase, said chamber being in the forrnof a cylinderand havin'g opposing-cylindrical walls, a liqni'd inertial mass in said chamber, a hollow paddle in said chamber and-immersedin'said liquid, said paddle being of substantially no effective mass when immersed imam liqu'id,"s'aid liquid being th'e inertial'rnassand the effective rotor of said device, a hinge for said paddle, said hinge being connected to said paddle, a mounting for said hinge in said chamber, said mounting being connected to said case and to said hinge, said paddle beingrotatabl-y mounted 'a'bout said hinge =0n the axis of said cylinder, for limited-angular motion ofsaid paddle about said axis and with nespect to said case 'on angular acceleration 'of sa id case about said axis, said paddle extending fromon'e wall to the opposing Wall, opposing edges of said paddle :being adjacent the opposing-cylindrical walls, an edge of each side of the paddle b'eing spaced from-the adjacent wall of the case, a baifiepo'sitioned in said-chamber .parallel to said paddle and spaced therefrom, said hinge -restraining motion of said paddle with respect to said casein the absence of angular acceleration of said case about said axis, and a motion sensing device connected to said paddle to sense the angular displacement ofisaidipaddle with respect to :said case.

Oliver May 2, 1944 Statham NOV. 9, 1948 

